Conventionally, while IC cards and mobile phones have been needed to be thinner and lighter, making an embedded semiconductor chip into a thin plate has been a problem to be solved, in order to meet the need. In order for that, the thickness of the wafer to be the base for the semiconductor chip has to be thin. Meanwhile, a circuit pattern is formed on the wafer.
To make the wafer thin, a method has been implemented in which a support plate having a through hole is bonded on the surface of the wafer on which the circuit pattern is formed, and after inverting it, the back surface of the wafer is ground. In addition, while the support plate for backup is bonded by an adhesive agent on the wafer that is made into a thin plate, when the separation of the wafer and the support plate is performed after predetermined processes, a dissolving solution for the adhesive agent is provided from outside of the support plate.
The dissolving solution reaches the adhesive-agent layer through the through hole formed on the support plate, and dissolves the hardened adhesive agent. The wafer thus separated from the support place is cut into respective chips by a dicing device.
Meanwhile, conventionally, when a circuit pattern is formed on a wafer, a resist resin is applied on the surface of the wafer using, for example, a spinner. However, the resist resin may attach to the end surface (edge) of the wafer or may run around and attach to the back surface of the wafer. Since the attached resist resin falls out within the apparatus and becomes a dust, it has been removed by edge rinse or back rinse, as has been well known conventionally.
However, the adhesive-agent layer is exposed in the state in which the wafer and the support plate are bonded by the adhesive agent, especially from the edge part between the wafer and the support plate. For this reason, when the resist attached to the peripheral edge surface of the wafer is removed by edge rinse in the removal process of the resist, the adhesive-agent layer is dissolved by the edge rinse. Then, the bonding strength between the wafer and the support plate decreases, and causes a disadvantage when the wafer is ground by a grinder and made into a thin plate. Furthermore, since the wafer and the support plate go through a various process in a state in which they are bonded, the resistance of the adhesive-agent layer is required against chemicals and the like used in the various processes.